Christopher Lane, co-owner of the Philadelphia Print Shop in Philadelphia, says he can do without maps made in the 20th century—they utterly lack what he loves: topographical mistakes. He can also do without maps created during the Middle Ages and earlier, but for the exact opposite reason: early mapmakers consistently got topological shapes and sizes outside their own villages wrong.

California an island? Find an old map that says so and it could be worth a boatload of money

That leaves Chris with that betwixt-era of maps drawn from the 16th through the 18th century—his favorite landscape in the cartographic field. "They didn't have global positioning satellites or even a way of figuring longitude, but they still got things right," Chris says, quickly adding, "but they also got things wrong."

For Chris, delight arises from what's wrong with these maps—the fantasy islands, imagined lakes, and non-existent continents. "What fascinates me about maps are their mythological features," Chris says. "That's my favorite topic." He suggests these maps for collectors interested in history and mythology ... and a bargain.

Mythical Islands
"The most common non-existent places to appear on old maps are islands," Chris notes. "In the early days of navigation, it was very hard to exactly place the location of a newly discovered island." Sometimes imaginings were mistaken for hard land. "Low-lying clouds could be thought to be islands, so many shown on maps either didn't exist or didn't exist where they were shown." A map drawn 400 years ago by one of the giants in the mapmaking field, Abraham Ortelius, depicted two fictitious Atlantic islands named "Los Jardines" and "Las dos Hermanos." These islands exist, but nowhere near where they were drawn. "If you had a ship and went looking for islands where these are shown, you wouldn't find anything," Chris says.

Legend also fed the addition of fictional islands. Ortelius added the island of "Sept Cites," or "Seven Cities," to his Atlantic Ocean. The fantom island came from the legend that seven Portuguese bishops led a group of refugees to an island with seven cities after the Muslims overtook Portugal in the 8th century. And in the northern Atlantic, Ortelius drew St. Brendan's Island, another imaginary isle that the Irish monk Brendan supposedly sailed to.

The Island of California
Chris' favorite island fantasy, and perhaps the most famous, is California, that West Coast state that mapmakers launched into the Pacific in the early 17th century. In earlier maps, such as one drawn by Francisco de Ulloa in 1539, the California area was accurately shown as part of North America. Father Antonio de la Ascension, who traveled to California in 1602, might have been the one who committed this geographic gaffe. In his journal of the trip, he wrote that California was separated from the American continent by the "Mediterranean Sea of California."

European mapmakers soon translated these words into new maps. And once the influential Dutch mapmakers put California to sea, it didn't land again for over a century. Even after Father Kino proved in 1705 that the Gulf of California only came up as far as what is now known as Baja California, creating a peninsula, many mapmakers, copiers as much as creators, drew the area as an island until 1747, when King Ferdinand VII of Spain issued an edict declaring California part of the mainland. Maps depicting California as an island are almost always worth more than accurate portrayals. "Graphically, it's just neat," Chris says. "It's such a wonderful and obvious mistake."

Other Misguided Maps
The antique map world is full of mythical continents, kingdoms, and lakes as well as islands. The continent of Antarctica was first imagined by cartographers who supported the belief that another southern landmass was necessary to balance the large swaths of land in the Northern Hemisphere. Mapmakers erased it from the globe until explorers convinced them that the fictional continent was real.

There's also the land of riches known as the Kingdom of Prester John, believed to lie in Asia for the better part of the 12th and 13th centuries. Since travelers could not find it on that continent, mythmakers moved it to Africa in the 1400s and mapmakers followed suit. In the 1600s, mapmakers added mythical lakes to Florida.

Map Histories
"I think what makes these maps so interesting is their history," Chris believes. "You need to get into the myth and study the history of the myth and put it in historical context." One of the most influential mistakes in the history of cartography was the depiction of the Pacific Ocean right next to the Atlantic in the Carolina and Virginia region. That myth was started by the Italian explorer Giovanni de Verrazano, who swore he saw the Pacific while sailing along the Atlantic coast (what he probably saw was Pamlico Sound across the outer banks of North Carolina or Chesapeake Bay). The English set down in Jamestown, at least in part because they believed it would be an easy portage to the Pacific and its riches, Chris notes. "Many of these maps affected history," Chris says.

By investigating these map myths and learning their histories you can often find interesting cartographic mistakes others have missed. "If you know what you're doing and looking for, you can pick up some bargains in the field," Chris says.

Large maps with spectacular mistakes, such as the island of California, can sell for thousands of dollars. But Chris says maps with less spectacular mythic additions can sell for just a few hundred dollars. Maps with mythological features are also readily available, as most drawn between the 16th and the 18th century contained one example or another.